1. Field of the Invention
The present invention relates to killing pathogenic microorganisms, removing contaminants and water from solid wastes so that the disinfected, washed and dewatered solid waste can be reclaimed, recycled or discharged into a sanitary landfill site for ultimate disposal. More particularly, the present invention relates to a multi-stage, single reactor, purification system for removing pathogenic microorganisms and contaminants from solid wastes.
2. Description of the Prior Art
The use and preservation of our natural and environmental resources continues to present conflicting priorities. On the one hand, there is the municipal, industrial, commercial, military and residential priority of growth, resulting in the dumping or discharging of contaminated solid wastes, such as contaminated soils, spent animal bedding, spent diapers, onto our land. On the other hand, the priority of preserving our environment and conserving our resources cannot be left unchecked. The complexities and costs for preserving our environment and conserving our resources have escalated to a point where disposal of hazardous, infectious, and toxic solid wastes by conventional pollution control apparatus and systems is stifling municipal, industrial, commercial, military, and residential growth. A balance between human progress and environmental conservation can be achieved only by further development of innovative pollution control apparatus and systems which are both cost-effective, and technically efficient.
The soil contaminated by the leaking underground storage tanks, accidental hazardous spills, and illegal dumping can not be remediated by conventional processes, such as soil venting, stabilization and fixation, washing and incineration. Soil venting is effective only when the soil is contaminated by volatile organic compounds (VOCs). Stabilization and fixation process is very expensive and is effective only for stabilizing and fixing certain hazardous substances. Conventional soil washing is practiced in conjunction with hydrocyclones and froth flotation, and is not effective for washing out infectious microorganisms. Incineration is another conventional process for reclamation of contaminated soil which is very effective, very expensive and frequently causes air pollution problems.
So far there has been no cost-effective process or apparatus for proper disposal of solid wastes from hospitals, clinical laboratories, biological laboratories and animal research institutions. Their solid wastes are generally labeled as "bio-hazardous" and disposed of by at least one of the following methods: (a) proper commercial transportation and sanitary disposal; (b) in-house incineration; (c) in-house sterilization and commercial sanitary disposal; (d) in-house sterilization and municipal sanitary disposal; (e) unsafe municipal disposal; (f) unsafe commercial disposal; (g) illegal dumping; and (h) unsafe or illegal landfill. Of the aforementioned options for disposal of bio-hazardous solid wastes, the first method (proper commercial transportation and sanitary disposal) is technically feasible, but economically unfeasible. All other methods are questionable.
The present invention involves the use of cationic surface active agents (cationic surfactants) and other disinfectants for disinfecting and cleaning a contaminated solid waste, and the use of mixing and expulsion means for processing and dewatering said solid waste.
While many cationic surface active agents are effective for disinfecting and cleaning solid wastes, the preferred cationic surface active agents to be used in this invention are quaternary ammonium compounds which may be regarded as equivalent to a substituted ammonium chloride salt molecule that has all four hydrogen atoms replaced by organic radicals. However, there is a difference in chemical characteristics. Ammonium chloride is a salt of a strong acid and a weak base, while organic quaternaries are salts of a strong acid and a strong base. Although common quaternary salts to be used in this invention are chlorides, there may be exceptions.
Said quaternary ammonium compounds, being cationic surface active agents, are compatible with nonionic materials and other cationic materials.
Said quaternary ammonium compounds are water soluble to varying degrees and generally insensitive to the presence of low concentrations of water soluble mineral salts; said quaternary ammonium compounds are not precipitated by hardness in water. With organic anionic materials, such as soaps, alkyl aryl sulfonates or other anionic synthetic detergents, an insoluble quaternary ammonia salt is formed by neutralization.
Said quaternary ammonium compounds of this invention all lower surface tension of water effectively and all have strong hydrophilic character, which are important properties for said quaternary ammonium compounds to be used for wetting, emulsifying, and cleaning solid wastes.
The quaternary ammonium compounds as well as other cationic surface active agents can be quantitatively determined by the methods invented by Lawrence K. Wang (U.S. Pat. No. 3,969,076, Jul. 13, 1976; U.S. Pat. No. 3,992,149, Nov. 16, 1976).
Treatment of wells with fluids containing a quaternary ammonium compound and other complexes was invented by Othar Kiel (U.S. Pat. No. 3,760,881; Sept. 25, 1973). A calcium base grease containing a quaternary ammonium compound and lead naphthenate for rust inhibiting was disclosed by William Scott on Nov. 30, 1971 (U.S. Pat. No. 3,623,982).
U.S. Pat. No. 3,165,465, which was issued to Charles L. Ray et al on Jan. 12, 1965, relates to the use of quaternary ammonium compounds for flocculation and settling of liquid suspensions of finely divided minerals. The present invention relates to the use of quaternary ammonium compounds for disinfection and cleaning of slid wastes.
A pressurized device which was developed by Svatopluk Mackrle et al on Feb. 25, 1965 (U.S. Pat. No. 3,429,442) for treatment of liquid contains several zones within a vessel in which a sedimentation and dewatering zone surrounds a sludge blanket zone, which in turn, surrounds a filter bed zone. The present invention relates to an enclosed, but not pressurized, reactor for treatment of solid wastes.
Burkert et al discovered that the addition of small quantities of aliphatic organic amine compounds (cationic surface active agents) to ammonium polyphosphate solutions produced from wet process superphosphoric acid and ammonia brings about a flotation of carbonaceous chars in a surface froth, and that the bulk of the carbonaceous material can thus be removed in the froth, in accordance with the U.S. Pat. No. 3,630,711 issued to them on Dec. 28, 1971. Another U.S. Pat. No. 3,969,483, which was issued to John M. Stinson et al on Jul. 13, 1976, also relates to removal of carbonaceous matter from ammonium polyphosphate liquids using aliphatic amine and quaternary ammonium compound. In the invention of Stinson et al, the particulate carbonaceous matter and a minor portion of the input ammonium polyphosphate liquid are withdrawn from the top of the separation vessel and processed into fluid or solid fertilizers. In the present invention, the added quaternary ammonium compounds react with organic anionic materials (such as soaps, alkyl aryl sulfonates or other anionic snythetic detergents) to form insoluble quaternary ammonium salts which are used as fertilizer fillers because of their high nitrogen content. However, the phosphorus content of the present invention's insoluble quaternary ammonium varies with varying the solid wastes to be treated.
In accordance with Harvey M. Goertz's invention (U.S. Pat. No. 4,378,238, Mar. 29, 1983), a controlled release particulate composition can be prepared by the reaction of urea and formaldehyde comprising polymeric nitrogen in the form of methylene urea polymers of varying chain length. Goertz's invention does not relate to quaternary ammonium compounds.
Roland E. Weber et al were awarded three U.S. Patents, one on Apr. 29, 1971 (U.S. Pat. No. 3,698,558), one on Oct. 31, 1973 (U.S. Pat. No. 3,887,470) and one on Mar. 29, 1977 (U.S. Pat. No. 4,165,283), and all said three U.S. Patents are concerned with anti-pollution devices for removing deleterious particles and matter from liquid, using purification means, collection means and compaction means. The purification means of U.S. Pat. Nos. 3,698,558 and 4,165,283 is filtration; while the purification means of U.S. Pat. No. 3,887,470 is sedimentation. The present invention relates to disinfection, cleaning, collection and dewatering of solid wastes, using cationic surface agents (including mainly quaternary ammonium, compounds), and chemical disinfectants (ozone, chlorine, hypochlorite, peroxide, permanganate), and is not concerned with filtration.
An aerobic sewage treatment method and apparatus for use with a conventional septic system collection tank was patented by Charles Traverse (U.S. Pat. No. 4,002,561; Jan. 11, 1977), whose invention relates to mixing and aeration for stimulation biological reactions in a vessel. The present invention relates to mixing and gas distribution for generation chemical disinfection reactions or anaerobic biochemical reactions in a vessel.
A wastewater and solid processing system invented by Milton Bruckner et al on Mar. 18, 1980 (U.S. Pat. No. 4,193,869) relates to air bubbling, filtration and chlorination (disinfection). The present invention does not relate to air bubbling and filtration
Two inventions by Wei-Chi Ying et al (U.S. Pat. Nos. 4,623,464, Mar. 21, 1985; and 4,755,296, Jul. 5, 1988) relate to air bubbling, mixing, aerobic biological reactions, and physical adsorption in open vessels for liquid treatment. The present invention, however, relates to mixing, gas distribution of disinfecting gases (instead of air), disinfection reactions for killing microorganisms, anaerobic biochemical reactions (instead of aerobic biological reactions), in enclosed vessels (instead of in open vessels).
The method for the deoxidation of chlorinated water, more particularly sea water, by means of a low oxygen content stripping gas was patented by Charles Mandrin on Jun. 26, 1990 (U.S. Pat. No. 4,937,004). The wastewater from the enclosed reactor and the expulsion chamber means of this invention contents quaternary ammonium compounds and/or other disinfectants and is to be treated by chemical reduction and neutralization (instead of gas stripping).
An improved gas dissolving and releasing system involving the use of multi-stages of porous gas dissolving media at the center and near the wall of a pressure vessel was patented by Lawrence K. Wang et al (U.S. Pat. No. 5,049,320; Sept. 17, 1991). Although there are many similarities between the U.S. Pat. No. 5,049,320 and the present invention, there are many dissimilarities between the two. The present invention relates to slid waste disinfection and dewatering in an enclosed, but not pressurized, reactor.
A sludge treatment multi-stage process and apparatus thereof for sludge concentration and liquid stream treatment was disclosed by Lawrence K. Wang et al in their U.S. Pat. No. 5,068,031, issued on Nov. 26, 1991. Although many technologies used in the U.S. Pat. No. 5,068,031 are similar to that used in the present invention, such as solids-water separation, multi-stage process operation, solid concentration, gas distribution, mixing, etc., the present invention relates to a completely different apparatus and a different process. The present invention is concerned with a solid waste treatment multi-stage process and apparatus thereof for solid waste disinfection and concentration.
Removal of volatile compounds and surfactants (including quaternary ammonium compounds) from liquid was disclosed by Lawrence K. Wang et al in their U.S. Pat. No. 5,122,165, issued Jun. 16, 1992. Their Wang process system invovles pumping, gas stripping in an enclosed reactor, foam collection, wet scrubbing, carbon adsorption, and carbon regeneration. The present invention relates to slid waste disinfection in an enclosed reactor, solid waste dewatering in an expulsion chamber means, and wastewater treatment in a chemical reduction and neutralization means.
One of quaternary ammonium compounds (cetyl dimethyl benzyl ammonium chloride), known as CDBAC or CETOL, was demonstrated by Lawrence K. Wang et al (Water Treatment, Volume 7, pages 1-16, 1992) to be an effective disinfectant. Another quaternary ammonium compound (alkyl dimethyl benzyl ammonium chloride), known as ADBAC or ARQUAD B-100, exhibits effective microbidical activity against various organisms such as molds, algae, and bacteria.
It is, therefore, an object of the present invention, to provide a new and improved purification system which kills pathogenic microorganisms, and removes contaminants and water from solid wastes, so that the disinfected, decontaminated, and dewatered solid waste can be sanitarily disposed of by landfill or reclaimed for reuse.
Another object of the present invention is to provide a pretreatment apparatus which is useful for hospitals, clinical laboratories, biological laboratories, and animal research institutions to pretreat their bio-hazardous solid wastes.
Still another object of the present invention is to provide a solid waste pretreatment apparatus which provides a compact, single vessel, and involves a multi-stage operation.
A further object of the present invention is to provide a relatively inexpensive, fully automatic, easy to operate solid waste purification system.
Another object of the present invention is to provide a solid waste purification system in processes where especially disinfected solid materials are required.
A still further object of the present invention is to salvage the contaminated solid material (such as soil) for reuse as the agricultural top soil, and to salvage the processed water containing nitrogen and phosphorus as the fertilizer.
A still further object of the present invention is to develop a biological flotation process for thickening of biosolids (including but not being limited to activated sludge) by an anaerobic sequencing biological reactor of this invention.